Standard-setting organizations such as 3GPP (3rd generation partnership program) are considering and standardizing PWS (public warning system), which is a platform for transmitting emergency information. PWS regulates functions for notification or transmission of warning notification (hereunder, referred to as alert) to several mobile stations (UE: user equipment). PWS is classified into ETWS (earthquake and tsunami warning system) and CMAS (commercial mobile alert system).
Non-patent Document 1 discloses a sequence of alert notification performed by means of PWS. An example sequence of an alert notification is described, with reference to FIG. 14.
A CBS (cell broadcast service) 50 notifies a CBC (cell broadcast center) 40 of alert content, notification area, and notification period, using an emergency broadcast request message (step S1001). Based on the received information such as notification area, the CBC 40 identifies an MME (mobility management entity) 30 to which a write-replace warning request is to be transmitted. The CBC 40 notifies the identified MME 30 of the alert content, the notification area, and the notification period, using a write-replace warning request message (step S1002). Upon receiving the alert content, the notification area, and the notification period, the MME 30 notifies the CBC 40 of information that indicates these pieces of information as having been received, using a write-replace warning response message (step S1003).
Furthermore, based on the received information such as notification area, the MME 30 identifies a base station (eNB: eNodeB) 20 that performs alert notification. The MME 30 notifies the identified base station 20 of the alert content, the notification area, and the notification period, using a write-replace warning request message (step S1004). The base station 20 identifies the cell that performs notification, based on the notification area. Moreover, the base station 20 notifies the mobile station 10 of the identified cell of the alert content, using SIB (system information block) 12 (SIB type-12) of BCCH (broadcast control channel) (step S1005). If another alert is being notified to the mobile station 10, the eNB 20 performs notification of several alerts in a time divisional manner. The mobile station 10 receives the alert notified by the eNB 20. Non-patent Document 2 discloses that alerts can be transmitted in a manner of being divided into several segments.
The notification cycle of an alert to be notified to the mobile station 10 by the base station 20 is regulated as a repetition period or extended repetition period in Non-patent Document 3. The notification cycle of an alert is set in a range between 1 second to 131071 seconds.